1808 mystery eruption

A 1991 study of Antarctic and Greenland ice cores, however, found a sulfate spike in early 1809, roughly half that of the 1815 eruption of Mount Tambora.

[2][8] The analysis of sulfur isotopes shows a complex time-evolving pattern, suggesting multiple eruptions that caused the 1809 sulfate layer and global cooling, consistent with the presence of different geochemical tephra populations during this period.

[4] Caldas' and Unanue's accounts indicated the existence of a stratospheric aerosol veil spanning at least 2,600 kilometres (1,600 mi) into both northern and southern hemispheres.

[4] The south-western Pacific Ocean between Indonesia and Tonga is an area in the tropics to the west of Colombia and Peru with candidate volcanoes and with little reporting at that time.

The Chilean Putana volcano also had a major eruption around this time, with an approximate date of 1810 (with a 10-year margin of error), but it is located 22 degrees south and therefore slightly outside the preferred latitude range.

Sulfate concentration in ice cores from Greenland , dated by counting oxygen isotope seasonal variations: A large unknown eruption occurred somewhat before the year 1810. [ 1 ] The peak after 1815 was caused by the Mount Tambora eruption .